1. Field of the Invention
The present invention relates to a waveform signal converting apparatus which converts a waveform signal representative of a musical tone waveform into a desirable waveform signal.
2. Prior Art
In the conventional waveform signal converting apparatus, the output waveform signal must be univocally determined by the input waveform signal. Because of its simple construction using the converting elements or conversion tables, the input waveform signal is directly converted into the corresponding output waveform signal which is predetermined in advance.
However, in the field of the signal processing, simulation analysis, musical tone synthesis and the like, it is necessary to process the signal non-linearly. In other words, it is necessary to carry out the waveform conversion based on the hysteresis loop.
For example, when converting the waveform signal whose value is to be increased or decreased, the waveform conversion must be carried out such that the conversion locus will be differed between the signal increasing event and signal decreasing event.
Meanwhile, the conventional waveform signal converting apparatus can carry out the simple non-linear waveform conversion. However, the conventional apparatus cannot carry out the waveform conversion such that the hysteresis loop is produced. Hereinafter, such waveform conversion is called "hysteresis waveform conversion".
In addition, there is another problem in that the conventional apparatus capable of carrying out the non-linear waveform conversion must be complicated in its construction.